It is known to apply a liquid to a web by first passing a foraminous screen through a bath of the liquid and then blowing the liquid with air or steam from the screen onto the web by means of a slot nozzle whose opening is arranged transverse to the displacement direction of the web past the nozzle. In this manner one can obtain a very even coating in a high-speed process without having to worry about the nozzle clogging. The screen can be formed as a foraminous drum (see Austrian patent document 175,956) or a loop (see German patent document 3,146,828) that dips into a bath of the liquid.
In order to be able in a production operation to vary the width of the strip of liquid, typically an adhesive, that is applied to the web, it has been suggested in German patent document 4,001,452 to set up the bath so that it is subdivided into individual compartments that can be selectively filled or emptied. Thus only a portion of the web need be wetted. Such an arrangement does allow the system to be adapted somewhat in a stepwise manner to different web widths, but still must almost always be set somewhat wider than the workpiece width so areas of the screen extending past the workpiece edges will become clogged.